What is the ruling on money taken for acting as an agent in selling a car, in the event that it cannot be registered in the buyer's name, knowing that the sellers have received the full amount for the car?

It is not permissible to take a Muslim's property except with his consent, based on the Almighty's saying: "Do not consume your property among yourselves unjustly, but [instead, let there be] a trade [deal] by mutual consent among you." And the Prophet, peace and blessings be upon him, said: "The property of a Muslim is not lawful except with his willing consent." So, when a seller sells an item and receives its price, he has obtained his right. It is not permissible for him to take any additional amount except for what results from the contract's implications, such as executing a power of attorney if the authorities do not permit disposition without it. In such a case, the seller must do it without a fee, unless there is a cost or hardship, in which case he may demand its expenses, unless custom dictates bearing them. It is permissible for the buyer to withhold part of the price to ensure the seller completes the procedures.